Long-term effects of theophylline in atrial fibrillation with a slow ventricular response

Early Detection of Atrial Fibrillation in Chronic Obstructive Pulmonary Disease Patients

Atrial fibrillation (AF) is an important medical problem, as it significantly affects patients' quality of life and prognosis. AF often complicates the course of chronic obstructive pulmonary disease (COPD), a widespread disease with heavy economic and social burdens. A growing body of evidence suggests multiple links between COPD and AF. This review considers the common pathogenetic mechanisms (chronic hypoxia, persistent inflammation, endothelial dysfunction, and myocardial remodeling) of these diseases and describes the main risk factors for the development of AF in patients with COPD. The most effective models based on clinical, laboratory, and functional indices are also described, which enable the identification of patients suffering from COPD with a high risk of AF development. Thus, AF in COPD patients is a frequent problem, and the search for new tools to identify patients at a high risk of AF among COPD patients remains an urgent medical problem.

Effects of permanent pacemaker and oral theophylline in sick sinus syndrome the THEOPACE study: a randomized controlled trial

BACKGROUND

Pacemakers and theophylline are currently being used to relieve symptoms in patients with sick sinus syndrome (SSS). However, the impact of either therapy on the natural course of the disease is unknown. We conducted a randomized controlled trial to prospectively assess the effects of pacemakers and theophylline in patients with SSS.

METHODS AND RESULTS

One hundred seven patients with symptomatic SSS (age, 73 +/- 11 years) were randomized to no treatment (control group, n = 35), oral theophylline (n = 36), or dual-chamber rate-responsive pacemaker therapy (n = 36). They were followed for up to 48 months (mean, 19 +/- 14 months). During follow-up, the occurrence of syncope was lower in the pacemaker group than in the control group (P = .02) and tended to be lower than in the theophylline group (P = .07). Heart failure occurred less often in patients assigned to pacemaker therapy and theophylline than in control patients (both, P = .05), whereas the incidence of sustained paroxysmal tachyarrhythmias, permanent atrial fibrillation, and thromboembolic events did not show any apparent difference among the three groups. Heart rate was higher in the theophylline group than in the control group. Both pacemaker therapy and theophylline improved symptom scores after 3 months of treatment; however, a similar improvement was observed in the control group.

CONCLUSIONS

In patients with symptomatic SSS, therapy with theophylline or dual-chamber pacemaker is associated with a lower incidence of heart failure; pacemaker therapy is also associated with a lower incidence of syncope. The therapeutic benefits of pacemakers and theophylline on symptoms are partly a result of spontaneous improvement of the disease.

Effects of theophylline and dibutyryl-cAMP on adenosine receptors and heart rate in cultured cardiocytes

The effects of chronic exposure to the adenosine antagonist theophylline (Theo) and dibutyryl cyclic-AMP, a membrane-permeant derivative of the second messenger 3', 5'-cyclic-AMP (cAMP), on contractions and adenosine receptor levels in cultured cardiocytes were studied. Binding of the A1-adenosine receptor antagonist [3H]8-cyclopentyl-1,3-dipropylxanthine ([3H]CPX) was used to monitor the level of the receptors in intact cardiocytes. Both Theo and cAMP stimulated the rate of contraction and also increased the density of adenosine receptors. The Bmax value for [3H]CPX binding to intact cardiocytes was increased by 45-47% following 4 days of exposure to either 50 microM Theo or 100 microM cAMP. Scatchard analysis indicated that the affinity of the A1 receptors for [3H]CPX remained unchanged (Kd 0.1-0.2 nM). No significant differences were observed in protein content or in cell number. A linear correlation was achieved between the level of A1-adenosine receptors and heart rate at various Theo and dibutyryl-cAMP concentrations, although Theo was more efficient in elevation of the receptor density. Increases of 82, 78, 138 and 235% in A1 receptor density and increases of 63, 59, 66 and 150% in heart rate were obtained following 5 days of treatment with 1, 10, and 1000 microM of Theo, respectively. It is concluded that there is a linkage between the rate of cardiac contractions and the level of adenosine receptors. Thus, changes in the density of adenosine receptors may compensate for chronic drug-induced changes in cardiac contractile activity so as to restore conditions to the normal state.